Complete Blood Count (CBC)

Hemoglobin (Hgb)

Q: What causes a high Hemoglobin (Hgb)?

Common causes of a high Hemoglobin (Hgb): Polycythemia; Chronic hypoxia; Dehydration; High-altitude living.

Q: What causes a low Hemoglobin (Hgb)?

Common causes of a low Hemoglobin (Hgb): Iron-, B12-, or folate-deficiency anemia; Blood loss; Chronic kidney disease; Hemolysis.

Q: What is a critical Hemoglobin (Hgb) value?

For Hemoglobin (Hgb), the commonly taught critical (panic) value is: 20 g/dL. Critical results are reported to the provider immediately under your facility's policy.

Normal range 12-17.5 g/dL (120-175 g/L SI). Specimen: Whole blood (EDTA).

Also known as: Hb, hgb.

12-17.5 g/dLCritical value: read below

Reference range

Combined adultg/dL

1217.5

SIg/L

120175

Meng/dL

13.517.5

Womeng/dL

1216

Adults. Separate men's and women's bands are published for Hemoglobin (Hgb) - read those rather than the combined band, which can call a result normal that is abnormal for the patient's sex. Pediatric ranges are not published here.

Hemoglobin (Hgb) reference range, specimen, and conversion details
Specimen	Whole blood (EDTA)
Conventional range	12-17.5 g/dL
SI range	120-175 g/L
Men	13.5-17.5 g/dL (135-175 g/L SI)
Women	12-16 g/dL (120-160 g/L SI)
Conversion factor	×10 (conventional → SI)
Critical value	< 7.0 g/dL (70 g/L) usually prompts transfusion consideration; > 20 g/dL
Panel	Complete Blood Count (CBC)

Convert any Hemoglobin (Hgb) result between units on the unit converter.

What is the normal range for Hemoglobin (Hgb)?

The standard teaching reference range for Hemoglobin (Hgb) is 12-17.5 g/dL in conventional units, or 120-175 g/L in SI units. This value is measured in whole blood (edta).

That band combines both sexes. Reported separately, men 13.5-17.5 g/dL and women 12-16 g/dL. A result inside the combined band can still be abnormal for the patient in front of you.

What is a critical Hemoglobin (Hgb) value?

For Hemoglobin (Hgb), the commonly taught critical (panic) value is: < 7.0 g/dL (70 g/L) usually prompts transfusion consideration; > 20 g/dL. Critical results are reported to the provider immediately under your facility's policy.

Source: Adult reference values compiled from Pagana & Pagana, Mosby's Diagnostic and Laboratory Test Reference, and Fischbach & Dunning, A Manual of Laboratory and Diagnostic Tests. Reference ranges vary by laboratory, method, age, sex, and population - always use the range printed on the actual result.

Above the range

What causes a high Hemoglobin (Hgb)?

Polycythemia
Chronic hypoxia
Dehydration
High-altitude living

What causes a high Hemoglobin (Hgb)? Read as its own page

Below the range

What causes a low Hemoglobin (Hgb)?

Iron-, B12-, or folate-deficiency anemia
Blood loss
Chronic kidney disease
Hemolysis

What causes a low Hemoglobin (Hgb)? Read as its own page

At the bedside

Nursing considerations

Men ~13.5-17.5 g/dL, women ~12.0-16.0 g/dL.
Assess for fatigue, pallor, tachycardia, and dyspnea with low values.
A rapid drop matters more than the absolute number - watch for active bleeding.

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